But who am I to tell people what they find fun? If a player says to me, "Hey, can we just skip this scene?" I will be happy to oblige. If they use a spell to accomplish the same end for the same reason, that's okay too. I see no reason to spend valuable free time on things people don't enjoy. Fast forward to the conflicts everyone wants, whatever that may be.
First: I was mainly interested in the question of spellcasting, and I appreciate the link to a previous thread on that topic. The same question has been raised, I think, with Guidance in social settings. (Thanks, jayoungr!)
Second: forum discussion about what moments in D&D are and aren't fun...
...well, those discussions are fun for some forum participants, and not for others. How meta!
If the PC stabs a guard (in front of the guard contingent of a large city's main gate), because a player is bored and wants to make the RP go away, then... well, that's an issue, which I'll address in a moment. If a PC casts a spell, as their equivalent of stabbing a guard to make the RP go away, then I respond just as I would if they had stabbed a guard.
Is there a significant difference between stabbing a guard to make the RP go away, and casting a spell to make the RP go away?
Okay, at this point I'm interested in a point raised, which is not about spellcasting, unless someone shows me that there's a difference between "stab the RP away" and "spellcast the RP away".
TOPIC TANGENT GAMMA (NOT ABOUT SPELLCASTING):
If a player assumes that this particular guard-PC interaction is going to be stock and boring, *and that it will take more than ten seconds*, then that's not giving me much benefit of the doubt as DM. I was going around the table and having each player describe their new PC and play out a snapshot of their entry to the city. If player #3 is bored by describing the first appearance of their new PC to the other players (and to me), then *player #3 can gorram tell me that they're bored*, and perhaps player 3 will make the great sacrifice of spending ten seconds on boring RP so that the rest of the table knows something about the new PC as a sentient humanoid, before we get to the FUN of damage per round.
Thing One: I am a human DM, not the CPU of a first-person-shooter. If a player is bored, then the player can *tell me with their own words*, rather than by the proxy of what their PC does to NPCs. I provide a more rewarding experience to players who TALK TO THE DM, than to players who use the indirect semaphore of having their PC stab guards in the game world.
Thing Two: table time is a limited resource. If the most interesting thing about player #3's new PC is the chain-gun hidden under the PC's overcoat, then player #3 can have their PC grunt and hand the guard a fistful of GP. That costs the table about ten seconds. Or you can go to a player-to-DM negotiation: "Dude, city guard interactions bore me". I might respond with "okay, mark off 5 gold in gate tolls, and let's move to the tavern scene." I might respond with "well, this is your new character's first close-up moment, is there some way that we can get a glimpse of their personality"? This conversation still escalates the table-time usage to *more* than the ten-second table-time cost of "grunt and pay". But maybe it saves table time overall, or results in a net increase of fun.
If, instead of admitting boredom, the player declares "I kill all the guards", is that going to take *less* than ten seconds to resolve?
I have, not much farther down the railroad, a fight scene in which the PC gets to use that chaingun on mutant zombie demon were-golems. Would you really rather spend table time killing all the guards, *at the expense* of table time spent gunning down mutant zombie demon were-golems? Keep in mind, we were going around the table, offering each player an entering-the-city mini-scene. Player #3 in that sequence avoided ten seconds of boring RP by spending ten minutes of the table's time on killing all the guards. This means, that when we resume going around the table, Player #4's PC arrives at a city gate which is now blocked by a pile of dead guards. Each player's choices have consequences for other players.